Plastering



Patented Apr. 12, 1932 UNITED srArs PA FRANK AMBROSIO, F BROOKLYN, NEW YORK, ASSIGNOR OF ONE-THIRD '10 HARRY T, oFFi'cE' GRASSER, OF LONG BEACH, NEW YORK PLASTERING No Drawing.

This invention relates to plaster and has for its object the provision of certain improvements in plastering. More particularly, the invention aims to provide an improved method of plastering which substantially 13 sion, as a new article of commerce, of a novel plaster composition, particularly adapted for finishing purposes.

In applying plaster upon such foundations as laths and the like, it has heretofore been the common practice to first apply directly on the laths (or other appropriate foundation) a relatively thick layer of coarse plaster,

thinner layer or coat of fine finishing plasfY ter. The first layer of coarse plaster has commonly been made up of about 1 part of neat gypsum plaster and about 3 parts of sand with sufficient water to form a mass of the desired consistency. Commercial neat gypsum plaster, as it ordinarily appears on the market, contains about 85% of calcined gypsum and the remaining is made up of hydrated lime, clay, asbestos, fibre and repreferably contains hydrated finishing lime tarder. About 3 to 4 days are usually required for the drying and hardening of this first layer of coarse plaster. The fine or finishing coat of plaster is commonly made up of about 5 parts of hydrated finishing lime and about 1 part of plaster of Paris with sufiicient water to form a mixture of the desired consistency. This finishing coat cannot be applied to the layer of coarse plaster until the latter has dried and hardened, and about 3 days are required for the drying of the finishing coat of plaster. It is thus a week, and frequently much longer, before a plastered wall is completed and ready for decoration by papering, painting or the like.

The present invention involves the application on an appropriate foundation of two Application filed January 16, 1931. Serial No. 509,271.

ond layer of plaster, applied directly on the first layer while the latter is still wet, is a stronger and more rapid setting plaster than the first layer. The first layer of plaster may be considerably thinner than the heretofore customary first or coarse layer of plaster and v the second or fimshmg layer of plaster may be somewhat thinner than the heretofore customary finishing coat of plaster.

Each of the plaster layers of the invention consists in large part of gypsum plaster, and v the second or finishing. layer contains in addition a substantial .amount of plaster of Paris; the combined amount of gypsum and when this has set and dried to apply a plaster and plaster of Paris being preferably about to of the total plaster composition.

The first layer of plaster may advantageously be made up of gypsum plaster and sand with the gypsum plaster in excess of the sand. It is now my preferred practice to ,7

make up the plaster for this first layer of approximately 2 parts (say 60 to 75%) of neat gypsum plaster and 1 part of sand.

The plaster for the finishing coat or layer and an inert strengthening material, in addition to gypsum plaster and plaster of Paris.

finishing plaster of approximately 2 parts of neat gypsum plaster, 2 parts of plaster of Paris, 1 part ofhydrated finishing lime and 1 part of marble dust or other appropriate inert strengthening material.

In practicing the invention, the first layer of plaster is applied directly on the laths or The first other appropriate foundation. Because of its relatively quick setting property the plaster should be applied as expeditiously as practicable. The second or finishing layer of plaster is applied directly on the wet first layer of plaster and must be worked rapidly since in its preferred form it sets or hardens in from one to two hours. The finishing layer of plaster is well adapted to produce the prevailing popular art-craft eiiects, and it is accordingly my preferred practice in applying the finishing coat to rapidly work it so as to produce such effects before the plaster begins to take on a permanent set.

One of the characteristic features of novcity of the present invention is the ability to apply the finishing layer of plaster to the first layer of plaster while the latter is wet. As a matter of fact, my experience in practicing the invention indicates that the first layer of plaster should be wet when the finishing layer is applied thereto, since otherwise the-first layer of plaster so rapidly absorbs moisture from the finishing layer as to prevent proper working thereof. The rapid setting or hardening of the finishing layer appears also to prevent cracking of the first layer. In other words, the first layer does not completely dry or harden for some time after the finishing layer has set and hardened, and the finishing layer thus appears to provide a hard protective coating on the first layer which effectively prevents cracking or rupture of the latter. It thus becomes possible by the practice. of the invention to completely form a finished plastered wall in about one days time, the wall being then ready for the application of any desired decorative efiects.

I claim:

1. The improvement in plastering which comprises applying to an appropriate foundation a layer of a relatively strong and quick-setting gypsum plaster, and applying to said layer of gypsum plaster while still wet a layer of astronger and more rapid setting plaster.

2. The improvement in plastering which dation a layer of a relatively strong and quick-setting plaster, and applying to said layer of plaster while still wet a layer of a relatively stronger and more rapid setting plaster containing from to 75% of gypsum plaster and plaster of Paris in approximately equal amounts.

5. The improvement in plastering which comprises applying to an appropriate foundation a layer of plaster containing gypsum and sand with the gypsum in excess, and applying to said layer of plaster while still wet another layer of plaster containing gypsum plaster, plaster of Paris and hydrated finishing lime with the gypsum and plaster of Paris each in excess of the lime.

(3. The improvement in plastering which comprises applying to an appropriate foundation a layer of a relatively strong and quick-setting gypsum plaster, and applying to said layer of gypsum plaster while still wet another layer of plaster containing gypsum plaster, plaster of Paris and hydrated finishing lime with the gypsum and plaster of Paris each in excess of the line.

7. The improvement in plastering which comprises applying to an appropriate foundation a layer of a relatively quick-setting gypsum plaster, and applying to said layer of gypsum plaster while still wet another layer of a relatively more rapid setting gypsum plaster.

In testimony whereof I aflix my signature.

FRANK AMBROSIO.

comprises applying to an appropriate foun- 

